Thioacetic Acid (CAS 507-09-5) — Top Note Fragrance Ingredient
Thioacetic Acid
CAS 507-09-5
What Is Thioacetic Acid?
Thioacetic Acid (CAS 507-09-5) is an aroma chemical used as a fragrance and flavour ingredient. Its odour is described as sour, sweet and fruit, placing it as a top note with high volatility. With a molecular weight of 76.11 (formula C2H4OS), it is handled by perfumers as a building block for compositions where a sour character is desired. The data below is compiled from public chemical and regulatory sources.
Safety Profile
USE WITH AWARENESS
What Does Thioacetic Acid Smell Like?
The odour profile of Thioacetic Acid is reported as sour, sweet, fruit, fish, garlic, spices, cold, burnt, acid, warm, musky, sweaty, ammonia/urinous, decayed, wood, grass, flower, chemical, edible. The dominant facet is its sour character, with the remaining notes adding nuance and complexity. As a top note it contributes to the opening of a fragrance. Perceived intensity and exact character depend on concentration, the carrier and the surrounding accord.
Scent Profile
Profile derived from public odour-descriptor data; relative, not absolute.
Chemistry & Properties
The Chemistry
Thioacetic Acid has the molecular formula C2H4OS and a molecular weight of 76.11 g/mol. Its canonical SMILES representation is CC(O)=S. Its reported log P (XLogP) of 0.8917 indicates a moderately polar molecule, which informs how it partitions in a formula. Physical constants below are drawn from PubChem and EPA CompTox public datasets.
Physical & Chemical Properties
| Molecular Weight | 76.11 g/mol |
|---|---|
| Boiling Point | 93.00 °C |
| Melting Point | -17.00 °C |
| Flash Point | 11.11 °C |
| Density | 1.07 g/cm³ |
| Vapor Pressure | 25.37 mmHg |
| Water Solubility | 4.01 g/L |
| XLogP | 0.8917 |
Perfumer Guide
Alternatives & Comparisons
Ingredients occupying a similar odour space — useful as substitutes or companions when Thioacetic Acid is unavailable or restricted.
Shares bakery, sweet, fruit character — a candidate substitute or companion in the same odour space.
Shares bakery, sweet, fruit character — a candidate substitute or companion in the same odour space.
Shares acid, ammonia/urinous, bakery character — a candidate substitute or companion in the same odour space.
Safety & Regulatory
⚠ Regulatory Disclaimer
General reference only. IFRA, REACH and EU Cosmetics Regulation standards update periodically. Consult the current IFRA Standards Library before formulating. Not legal or regulatory advice.
IFRA Status
No IFRA restriction recorded in the data set. This is not a guarantee of unrestricted status — always confirm against the current IFRA Standards Library.
GHS Classification
Signal word: Danger
Odour detection threshold (air): 0.0005 ppb — a literature-curated value indicating its potency in the vapour phase.
Open Thioacetic Acid in Fragrance Studio (Pro) for the calibrated vapour-pressure curve, the modelled odour-threshold estimate, and the substitute-matching engine across 2,900+ aromachemicals.
References & Sources
- PubChem Compound Summary (NIH) — search by InChIKey
- EPA CompTox Chemicals Dashboard — physicochemical & fate data
- IFRA Standards Library (49th / 51st Amendment)
Data: PubChem (NIH), EPA CompTox, IFRA. Last reviewed: Jun 2026.
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